Dr. Myra Finkelstein, University of California Santa Cruz – Condors and Lead Poisoning

In today’s Academic Minute, Dr. Myra Finkelstein of the University of California Santa Cruz explains how lead poisoning is slowing the recovery of the California condor.

Myra Finkelstein is a postdoctoral researcher in microbiology and environmental toxicology at the University of California Santa Cruz. Her research focuses on human impacts to marine systems with an emphasis on contaminant-induced effects. Her work has been published in a number of peer-reviewed journals and she holds a Ph.D. in Ocean Sciences from the University of California Santa Cruz.

California condors are North America’s largest terrestrial bird; with a wingspan of ~9 feet. In 1982 there were only 22 individuals remaining and to save condors from extinction captive breeding programs were established. The captive breeding program has been very successful, and today there are over 400 condors, approximately half of which are in zoos and the other half in the wild. However, this success is only due to the daily efforts of large numbers of zoo staff, biologists and volunteers, who maintain the breeding program, as well as monitor every wild condor almost every day.

The main threat to condors in the wild was believed to be lead poisoning but the full extent of this threat was not known. So, we performed a comprehensive study to investigate the impact and source of lead exposure to condors. We found that since the release program began condors have been chronically exposed to harmful levels of lead. Alarmingly, almost half of all condors in the wild in California have had blood lead levels that demonstrate poisoning severe enough to require medical treatment.

We also used lead isotopic analysis, which can often provide a signature of the sources of lead exposure, and showed that lead-based ammunition is the principal source of lead poisoning in condors. Condors are obligate scavengers and when they feed on a carcass that has been shot with lead ammunition they can inadvertently ingest some of the lead, and even a few very small fragments - equivalent to a couple of grains of sand - contains enough lead to poison a condor. Finally, we developed population models which revealed that the condor’s current apparent recovery is solely due to intensive ongoing management, and that if this management is stopped, the condors will once again be at risk of extinction within a few decades. Ultimately we determine that the condor’s only hope of achieving true recovery is dependent upon the elimination or substantial reduction of lead poisoning.